1. Field of the Invention
This invention relates to a tool exchange device for machining centers, in particular to a tool exchange device with simple structure and capable of automatically and swiftly exchanging tools during cutting processes.
2. Description of Related Art
FIG. 1 is a perspective view showing a tool exchange device disclosed in Japanese Patent Gazette TOKU KOU HEI 5-228709. As shown in FIG. 1, a first reduction gear assembly 10 and a second reduction gear assembly 20 are arranged to transmit the power from a motor 4.
The first reduction gear assembly 10 includes two bevel gears 11 and 12. A grooved face cam 51 and a concave globoidal cam 52 are respectively formed on the sidewalls of the bevel gear 12. The grooved face cam 51 is used to drive a shaft 31 to move upward and downward by way of a cam follower 511, and the helical cam 52 is used to drive the shaft 31 to rotate around its own axis by way of a plurality of rollers 311 affixed on the peripheral wall of the shaft 31. By this arrangement, a swap arm 30 affixed to the lower end of the shaft 31 can be driven to move upward and downward and simultaneously to rotate around the axis of the shaft 31 so to facilitate the exchange of tools.
The second reduction gear assembly 20 includes two spur gears 21 and 22. A plate cam 53 integrally formed with the spur gear 22 is used to drive a cam follower 531 which is connected to a toggle assembly 46. By this arrangement, the second reduction gear assembly 20 can drive a push-pull rod 41 to move upward and downward so as to facilitate the uncoupling of a tool 44 from the lower end of the push-pull rod 41 and the coupling of another tool 45 with the lower end of the push-pull rod 41.
In the above tool exchange device, two reduction gear assemblies 10, 20 are used, therefore large installation space is required and manufacturing cost is high. Furthermore, due to that the tool exchange device is connected with the head shaft of machining tools, the movement of head shaft has to carry the tool exchange device during cutting operation. Therefore, additional power is required and efficiency becomes low.